The inorganic anions in tobacco such as F−, Cl−, NO2−, Br−, SO4−, NO3− etc. have significant effects on the physiology of tobacco and the quality of tobacco products. If the tobacco leaf has high content of nitrate salts, the fume will have high content of compounds with nitro groups. Compounds with nitro and nitroso groups can cause the cancerations or toxications of animals; sulfur and chlorine have negative effects on the combustibility of cigarette; bromine can partially substitute for chlorine. Therefore, inorganic anions such as nitrate ions, nitrite ions, chloride ions etc., are important items in tobacco determinations. The organic acids in tobacco are intermediates of the tricarboxylic acid cycle in carbohydrate metabolism, which are closely related to the growth of tobacco. The organic acids in tobacco are divided into two categories, volatile and non-volatile. Volatile organic acids contain acetic acid, formic acid, propionic acid and the like. Volatile organic acids could generate fragrance which have been found to be good for tobacco. Non-volatile organic acids mainly contain binary acids and trinary acids such as citric acid, malic acid, oxalic acid and so on, and they make up more than half of the total content of organic acids in tobacco. Most of the organic acids are in the form of salts, containing nicotine, ammonia and inorganic ions such as calcium ion, potassium ion and sodium ion. The maturity of tobacco is related to the ratio of oxalic acid to citric acid and the higher the better. The organic acids such as malic acid, citric acid, oxalic acid, etc., are also conventional cigarette additives. Furthermore, organic acids, which have significant influences on the flavour and taste of tobacco. are primary materials for the synthesis of higher aliphatic acids, amino acids and proteins in plants, Therefore, the analysis of inorganic anions and organic acids in tobacco are of great importance.
Recently, chloride ion, nitrate ion and nitrite ion in tobacco are generally determined by continuous flow analyzer in tobacco industry. Though traditional chemical analysis method is mostly employed for the determinations of fluoride ion, sulphate ion and the like, it has the disadvantages of complication, long time-consumption, low sensitivity and so on. Although the continuous flow analyzer method is widely applied, it could not be used for the simultaneous determinations of inorganic anions as described above. It has been reported in the domestic literature that inorganic anions in tobacco are simultaneously determined by means of ion chromatography. The classical organic acid determination method is to carry out gas chromatography analysis or gas chromatography-mass analysis after the esterifications of organic acids, but this method also have the disadvantages of long time-consumption, complication, high reagent-consumption and so on. It has also been reported that reverse phase high performance liquid chromatography and ion chromatography are employed to determine the organic acids in tobacco. Perini F R et al. employs ion chromatography to determine the carboxylic acids with low molecular weights such as formic acid, acetic acid, propionic acid, lactic acid and inorganic anions such as F−, Cl−, NO2−, NO3− in tobacco products and auxiliary materials thereof. As reported in “Analysis of organic acids and inorganic anions in tobacco by ion chromatography and cluster analysis”, Acta Tabacaria Sinica, 15 (4), August 2009, the contents of 9 organic acids and anions in tobacco sample are determined by ion chromatography, however, such technology would not be able to comprehensively and accurately determine the components in tobacco and even has the deficiency that some components would not be separated and thus the contents of components to be tested would be incorrectly obtained. Taking the separation between malonic acid and malic acid for example, said technology does not take the disturbance between the two components into consideration, malonic acid and malic acid in tobacco would be simultaneously eluted, the content of malonic acid would be mistakenly counted for the content of malic acid, leading to determination errors.
By now, it has not been reported that 16 inorganic anions and organic acids in tobacco could be quickly determined on the basis of sample injection for once.